1. Field of the Invention
The present invention relates to a special amino acid mixture and dialysis solution for hemodialysis. The use of the amino acid mixture for preparing a solution suitable for hemodialysis is also set forth. The present invention also relates to a method and an apparatus for hemodialysis.
2. Discussion of the Background
Patients who suffer from impaired kidney function, or who do not even have kidneys, need the assistance of an external blood-purification system to purify the blood of toxic metabolic products. In such cases, peritoneal dialysis and hemodialysis have proved to be the methods of choice.
Heretofore, however, neither form of dialysis has completely made up for the lack of kidney function. In the case of hemodialysis, for example, a phenomenon known commonly as xe2x80x9cshrinking manxe2x80x9d becomes evident after prolonged treatment. This syndrome is blamed substantially on a protein-deficient nutritional condition. This deficiency condition has several causes, such as protein and energy metabolism disorders, hormonal imbalance and poor nutrient intake, and in the case of dialysis patients is greatly exacerbated by the net loss of amino acids from the plasma during dialysis, thus depriving the body of its needs for normal functioning.
Various therapies are currently being used to prevent and treat this deficiency condition (J. D. Kopple, Am. J. Kidney Diseases, 33, 180-185 (1999)). Besides special diets and nutrient supplements, dialysis patients sometimes also receive additional nutrients by artificial means. Besides enteral nutrition by esophageal tube, parenteral nutrition is also used. In this situation, the amino acids in the form of concentrated solution are either administered directly by means of a central venous catheter or are added to the blood returned to the body during dialysis treatment.
Although amino acid solutions of specially adapted composition (W. Druml, Miner. Electrolyte Metab., 24, 47-54 (1998)) have been used in certain cases for such parenteral nutrition, a satisfactory nutritional condition cannot be achieved with any of these methods (J. D. Kopple, Am. J. Kidney Diseases, 33, 180-185 (1999)). The reason is that, although the general nutritional condition is indeed improved by the additional nutrient supply, the disturbed protein metabolism which results from loss of kidney activity and which in turn leads among other consequences to unbalanced amino acid composition (S. Troupel et al., Amino Acids 2, 127-132 (1992)) is not alleviated, but instead can even be further exacerbated, since the supplied infusion solutions are oriented to the physiological condition and have a composition adjusted such that their relative concentrations of amino acids corresponds to the uptake thereof from the plasma into the cells and thus not to the concentration pattern of the plasma itself. Furthermore, when the amino acid solution is supplied during dialysis, a large part of the supplied amino acids is immediately removed once again via the dialyzer fluid.
Some attempts have therefore been made, by adding amino acids to the dialyzer solution in the concentration which exists in the plasma, to prevent at least the additional amino acid losses which occur during dialysis. All solutions used heretofore, however, lack the complete physiological spectrum of amino acids necessary (F. Quarto di Paolo et al., Int. J. Art. Org., 1978, 1, pp. 112 ff.; C. L. Abitol et al., J. Parenteral and Enteral Nutrition, 1984, 8, pp. 25 ff.; S. Fruend et al., Clinical Nephrology, 46, 64-66 (1996); C. Chazot et al., Kidney Int. 52, 1663-1670 (1997)). In fact, the already existing imbalances are even exacerbated by such measures. This dialysis method has therefore not been adopted as routine therapy, and has even been evaluated as too expensive and ineffective (T. Tepper et al., Int. J. Artificial Org. 4, 208-10 (1981)).
Accordingly, there remains a need for compositions suitable for hemodialysis which overcome the difficulties described above, and to methods of dialysis using such compositions.
It is an object of the present invention to provide an amino acid composition which is capable of preventing the loss of amino acids/from the plasma of a patient undergoing hemodialysis.
It is another object of the present invention to provide an amino acid composition which can be used to compensate for pathological amino acid imbalances in the plasma of a patient undergoing hemodialysis.
It is an another object of the present invention to provide an amino acid composition which, as compared to known compositions, is capable, to a higher degree, of preventing the loss of amino acids from the plasma of a patient undergoing hemodialysis and which can be used to compensate for pathological amino acid imbalances in the plasma of a patient undergoing hemodialysis.
The objects of the invention, and others, may be accomplished with an amino acid composition comprising the following proportion of amino acids, based on the total weight of the amino acids, listed in Table 1:
The results of using this amino acid composition containing all relevant amino acids for hemodialysis are, on the one hand, that the amino acid concentration imbalances in the blood plasma of sick patients are compensated for and, on the other hand, that amino acid migration into the dialyzate due to lack of osmotic pressure is prevented.
Thus, the objects of the present invention may also be accomplished with a dialyzer fluid containing the proportions of the amino acids described above.
The objects of the present invention may also be accomplished with dialyzer fluid comprising amino acids at the concentrations listed in Table 2.
The objects of the present invention may also be accomplished with a method of hemodialysis by dialyzing a patient in need thereof using the inventive amino acid composition.
The objects of the present invention may also be accomplished with a method of hemodialysis by dialyzing a patient in need thereof with a dialyzer fluid containing the amino acid composition of the invention.
The objects of the present invention may also be accomplished with an apparatus for hemodialysis with a dialyzer, comprising:
a first flow path for the blood of a patient,
a second flow path for a dialyzer fluid,
a semipermeable membrane separating the first and second flow paths,
a vessel for containing the dialyzer fluid, wherein the vessel has a connection for withdrawal of dialyzer fluid to be supplied by the dialyzer and has a connection for the return to the vessel of the dialyzer fluid arriving from the dialyzer,
wherein the vessel is sufficiently thermally insulated from the ambient air that there is no need for a heating means to control the temperature of the dialyzer fluid and to keep it constant throughout the duration of the dialysis treatment,
wherein the connection for withdrawal of the dialyzer fluid discharges at the upper region of the vessel and the connection for return of the dialyzer fluid discharges in the lower region of the vessel,
wherein the vessel contains a dialyzer fluid containing the amino acid composition of the present invention.
The amino acid composition according to the invention may be added to a dialyzer solution in the proportion required to obtain a dialyzer fluid which corresponds in composition and concentration to the amino acid plasma level of a healthy person. The subject matter of the invention, therefore, also includes a dialysis solution having the amino acid composition described above.